In the current climate of increasing incidence of disorders related to high cholesterol, in particular coronary artery disease (CAD), there is an increasing demand for effective cholesterol testing. Many epidemiological investigations have demonstrated the strong and independent inverse association of high density lipoprotein (HDL), measured in terms of either its cholesterol or apo A1 content, to risk of CAD. It is said that the risk of CAD increases 2-3% for every 10 mg/L decrease in HDL-cholesterol. Thus, higher HDL-cholesterol concentrations are considered protective. Conversely, higher concentrations of low density lipoproteins (LDL) are considered to have an adverse effect. Therefore, cholesterol tests should preferably not only indicate the total cholesterol levels, but also provide a measurement of the LDL cholesterol and HDL cholesterol levels.
The test procedures currently available to clinicians generally require a sample to be sent away to a laboratory test facility for such results to be obtained. This causes an undesirable time delay between test samples being taken from a patient and a diagnosis being reached. There is therefore a need for simple, effective and rapid methods for analysing the cholesterol content of body fluids such as blood or plasma, in particular methods that can provide results at the point of care. Preferred methods therefore will not employ specialist equipment, or require trained technicians to carry out. Further, any such method should preferably be capable of effectively distinguishing between cholesterol bound to HDL, and cholesterol bound to LDL.